On the earnings call Monday morning, Sotheby’s CEO Tad Smith declined to name the paintings. But he said that with one of them “the contribution was positive, and if we had had more bidding it would have been robustly attractive” to the company. The second painting, he said, “was a pricing error.”

Art industry sources say the second painting was Picasso’s 1932 work “Buste de Femme de Profil (Femme Ecrivant).” The work was estimated to sell for $45 million, and Sotheby’s guaranteed the seller a price of around that amount. Sotheby’s then had an irrevocable bid for $36 million, and it sold to the irrevocable bidder for $36 million. Even with the buyer’s commission, Sotheby’s ended losing between $6 million to $7 million on the painting, according to art market experts.

When he took over the company in 2015, Smith said that he would be disciplined when it came to guarantees. He said he would be “focused on returns on invested capital and being careful with shareholders’ money.”

Two paintings don’t make a trend. And Sotheby’s stock may well come back — especially since the overall art market remains strong and the important fall sales are shaping up to be solid.

But the tales of the Picasso and the Modigliani show that pricing and selling masterpieces is more an art than a science.